1. Field of the Invention
The present invention drawn to a plasma etching process of a semiconductor wafer. More specifically, the present invention is drawn to the monitoring and analysis of plasma to detect any problems encountered in the etching process.
2. Description of Related Art
In a standard plasma etching process of a semiconductor wafer, plasma is placed in a chamber which is usually a cylindrical vacuum chamber. A semiconductor wafer to be etched is placed at one end of the chamber and an electrical current is run through the plasma. As the wafer is being etched, the success of the etching can be determined by monitoring and recording emission elements emitted from the plasma.
A typical commercial vacuum chamber is made of stainless steel or aluminum. These chambers usually have one or more small windows which are approximately one inch in diameter. Since it is very difficult to take measurements through such small windows, special chambers have been developed to obtain the tomography of the plasma. The manufacture of these specialized chambers can be costly.
The invention of the present application eliminates the need to manufacture specialized vacuum chambers in order to determine the tomography of the plasma. This is accomplished by utilizing the existing windows found in typical commercial vacuum chambers to take proper tomographical measurements of the plasma. This will eliminate the need to manufacture specialized chambers saving time and money.
In one embodiment of the invention a device for monitoring emission elements emitted from a chamber has a lens array located in a position to receive emission elements from a chamber. The lens array has a plurality of lens array lenses. Each of the lens array lenses has a line of sight intersecting one another at a single point in front of the lens array.
A method for monitoring emission elements emitted from a chamber includes the steps of receiving emission elements through a lens array having a plurality of lens array lenses and positioning each of said lens array lenses so that each lens array lens line of sight intersects one another at a single point in front of the lens array.